Heat-dissipating means for electrical apparatus.



H. A. RHODES.

HEAT DISSIPATING MEANS FOR ELECTRICAL APPARATUS.

APPLICATION FILED SEPT. 13, 1 909.

Patented Jan. 17, 1911 UNITED STATES PATENT OFFICE.

HARRY A. RHODES, OF DENVER, COLORADO, ASSIGNOR TO THE UNIVERSAL MOTOR COMPANY, OF DENVER, COLORADO, A CORPORATION OF ARIZONA TERRITORY.

HEAT-DISSIPATING MEANS FOR ELECTRICAL APPARATUS.

Application To all wlwm it may concern:

Be it known that I, HARRY A. RHODES, a citizen of the United States, residing in the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Heat-Dissi ating Means for Electrical Apparatus; an I do declare the followin to be a full, clear, and exact description ot the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

My invention relates to improved means for dissipating" heat from electrical and other machinery or a paratus or material, but is more es ecially intended for dissipating the heat eveloped in the wires or conductors forming the coils of electrical-translatin devices.

It is a fact well known that when a' 0011- ductor is traversed by a current of electricity, the conductor is heated thereby to a definite extent in accordance with well known physical and electrical laws. The

heat thus developed may accumulate in the conductor to such an extent as to cause the.

burning and consequent destruction of the conductor or the attendant insulating material, or both, unless means are employed to preventundue heating of the conductors and insulating materials of apparatus of this character, as for example, the electromagnetic field and armature windings of dynamos and motors, etc. These machines may easily be destroyed by the heating etfeet of the operatin electrical current. Among the means so $211 employed for obviating said destructive efiects, I will cite the usual precautions taken by electrical machine designers to provide, so far as possible, for airventilation in open spaces surrounding the magnet windings or sections thereof, and by limiting the depth or other dimen sions of the magnet coil or section winding in proportion to the available air spaces, and by the provision of air ducts through the spiders and windings of the armatures, and in general to provide to as large an extent aspossible for an open or skeletonconstruction of the machine or apparatus to afford a maximum circulation of air through or adjacent to the windings. Such Specification of Letters Patent.

filed September 18, 1909. Serial No. 517,487.BEISSUED Patented Jan. 17, 1911.

tight case.

As the power of an electrical machine is directly proportional to the current given out or taken in by it, and as the safe current by which the conductor in the machine may be traversed, is limited by the maximum temperature which the conductor and insulating material will stand without damage, it is obvious that the capacity of a given machine may be increased if suitable means be provided to prevent an undue rise of temperature in the machine.

The object of my invention is to provide means, whereby the heat generated by the current in electrical machines, may be economically and safely conveyed or conducted from the various sections of the machine to adjacent, or other radiating volumes or surfaces, Where it is dissipated in accordance with the well known laws of heat radiation. For example, take the case of a simple electro-magnet spool or bobbin, constructed on a central iron core carrying metallic heads or end disks. Assume a proper length core to contain thirty convolutions of No. 16 B. & S. single cotton-covered wire and a depth or radius of the end disks to contain ten layers of this Wire. Assume also a sufiicient current to raise the temperature of the middle layer at the central point, 100 degrees Fahr. in live minutes. The rise of temperature is duev to the low heatconducting capacity of the cotton insulation lying between this point and the end disks, or the surrounding atmosphere; consequently if means he provided to increase the heat conductivity of these paths, the heat generated will he morerapidly conveyed away from the windings and dissipated by the adjacent end disks and surrounding atmosphere, thus preventing an undue rise of term perature in the coil. I accomplish this ob away. The efiiciency of this method, other thin s being equal, depends upon the relative eat-conducting values of the heat conductor chosen for serving the insulated conductor, being, for illustration, much higher for silver than for tin, zinc or carbon. In applying this method, I have obtained highly beneficial results by serving the coil, after each la er iswound on, with tin, silver or other oil, from one to three one-thousandths of an inch thick, and permitting the foil to overla the ends of the coil, thus connectin the oil with the metal end disks; but I 0 not confine myself to this method, as it is obvious that the insulated conductor may be served before winding on the core with a heat-conducting, non-1mpregnating foil, paint or paste; or such substance may be applied to the conductor during the process of winding; as, for illustration, pulverized tin, silver or lamp black worked to a non-impregnating-paste in alcohol, or other suitable matrix, may be applied by cbrush after or during the process of winding each layer, by which method the interstices between adjacent conductors, windings or con volutions may be practically filled with a heat-conducting, non-impregnating material much superior to the air normally present. It will thus be observed that, it is not my intention to treat the insulated conductors of electrical apparatus with a substance which shall impregnate or penetrate the insulation of these conductors, but simply to fill the spaces between and surrounding the same, or the convolutions, layers or windings thereof, in such a manner that a path or avenue of escape for the heat developed therein may be provided, said path being of such character that the heat will readily follow it and be rapidly and constantly removed and dissipated, practically as fast as it develops.

Having briefly outlined my improvement, I will proceed to describe the same in detail, reference being made to the accompanying drawing, in which is illustrated one form or embodiment of the invention.

In this drawing: Figure 1 is a section taken through a spool carrying a series of coils of insulated wire, the said coils being separated by layers of heat-conducting, nonimpregnating material for heat-dissipating purposes. Fig. 2 is a cross section taken on the line 2-2, Fig. 1. Fig. 3 is a detail view showing a sheet or section of relatively thin metal foil adapted for use in separating the layers or coils of insulated wire, when arranged as shown in Fig. 1. Fig. 4 is a spool upon whose spindle or core, a single layer or coil of wire is wound, the same being shown before the heat-conducting layer or substance has been applied.

The same reference characters indicate the same parts in all the views.

Let the numeral 5,.designate a spool composed of a core 6, and metal heads 7. Upon this core and between the heads, are wound coils or spiral layers 8, of insulated wire, the said layers or coils being separated by relatively thin sheets 9, of metal foil which is of such character that it has a high coefficient of heat conductivity, and which shall at the same time be sufiicicntly refractory to prevent fusion or softening at ordinary temperatures. These layers of sheet metal foil are applied after each coil or layer of wire is wound upon the spool, the said layers or coils being thus separated by the heat-conducting sheets from the innermost to the outermost layer of wire upon the spool. As shown in the drawing, the extremities of these sheets 9, are slotted or slitted, as shown at 10, to form a series of relatively short lips 12, the said lips extending a sufficient distance beyond the body of the sheet 9, to cause the lips to be outwardly bent or flared against the metal heads 7 of the spool, whereby the heat which uses these sheets as a path or avenue ofescape, is carried to the metal heads 7, taken up thereby and readily dissipated or discharged into the surrounding atmosphere.

In this drawing, it will be observed that no attempt has been made to illustrate more than a single form or embodiment of the invention. It will be understood, however, that many other formsof the nature heretofore outlined and non-im regnating in character may be employed, t ere being only one indispensible requirement or desideratum, viz: that the foil or substance shall be of such character as to form an easy path or avenue of escape for the heat developed within the coils or conductors of electrical apparatus, where the said coils, wires or conductors are so located, that the efiiciency of the apparatus may be increased by dissipating the normal heat development therein. Where instead of the thin sheet metal foil illustrated, a non-impregnating paste is employed, this may be spread upon the successive layers or coils of wire, as they are wound upon or applied to the spool or other apparatus.

Having thus described my invention what I claim is:

1. Means for dissipating heat from the coils or conductors of an electrical apparatus, comprising a spool upon which layers of coils or conductors are wound, a non-impregnating, heat-conducting substance ap-. plied to the spool and in engagement with the spool heads, the said substance separating the layers of coils or conductors thereof, and leading out of the conductors or coils to the air, forming a path for the escape of the heat developed in the apparatus, substantially as described. 7

2. The combination with a spool having esneeo metal heads and the conductors or coils thereof, of means applied to the said s 001, and separating the layers or coils thereo for heat-dlssipating purposes, said means including relatively thin layers of heat-conducting, non-impregnating material bent outwardly at their extremities and brought into engagement with the metal heads of the spool, the latter being of such character that, while possessing a high coeflicient of heat conductivity, it shall also be sufiiciently refractory to prevent softening or fusion at ordinary temperatures.

3. The combination with a spool having conductors or coils, of layers of sheet metal foil interposed between the conductors, coils or layers of coils of the apparatus, the extremities of the said sheets being slit and bent into engagement with the spool for heat-dissipating purposes.

4. The combination with a spool having metal heads and an electrical conductor arranged in layers or coils upon the spool, of

relatively thin layers of sheet metal foil interposed between the'coils or windings of the apparatus, and extending outwardly, the extremities of the said sheets bein brought into contact with the metal hea s of the spool for heat-dissipating purposes, substantially as described.

5. The combination with a spool having metal heads and electrical conductors arran ed in coils on the spool, layers of relative y thin sheet metal foil interposed bein presence of two witnesses.

I HARRY A. RHODES. Witnesses:

A. J. OBRmN, M. F. MANEY. 

